In recent years, an axial flow turbine of radial-inflow type which causes working fluid to flow in an axial direction to act on turbine blades of a turbine wheel and rotates the turbine wheel has been developed. Such an axial flow turbine of radial-inflow type is, for instance, considered to be advantageous in a small supercharger such as a turbocharger for an automobile, whose turbo rug is desired to be reduced by decreasing inertia.
Patent Document 1 discloses a turbocharger including an axial flow turbine of radial-inflow type configured such that exhaust gas from a scroll part acts on leading edges of turbine blades substantially in the axial direction.
Further, though not related to an axial flow turbine, Patent Document 2 discloses a mixed flow turbine for a supercharger configured to direct exhaust gas from a scroll chamber to a turbine impeller with a leading edge part formed diagonally to the axial direction. The mixed flow turbine has an intermediate property between a radial flow turbine and an axial flow turbine.